CN110612654B

CN110612654B - Motor for vehicle

Info

Publication number: CN110612654B
Application number: CN201880030444.6A
Authority: CN
Inventors: V·拉格亨特库马尔拉查巴特尼; S·杰贝兹迪纳加
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2017-04-05
Filing date: 2018-04-04
Publication date: 2022-04-08
Anticipated expiration: 2038-04-04
Also published as: WO2018185667A1; TWI782005B; TW201838291A; CN110612654A; EP3607638A1

Abstract

The present subject matter discusses a motor and a sensing arrangement for core saturation and a method of detecting core saturation. The present subject matter proposes that an auxiliary winding having at least one tooth is wound around at least one of the stator teeth along any of the phases of the electrical machine. The ends of the wires are provided to a signal conditioning circuit that filters noise from the signal. The filtered signal is provided to an ADC (analog to digital converter) pin of the controller to digitize the signal value.

Description

Motor for vehicle

Technical Field

The present invention discusses a motor and a core saturation sensing arrangement and a method of detecting core saturation.

Background

Electric machines are generally composed of a stator and a rotor. The configuration of the rotor for different motors is also different based on the motor topology. The rotor of the induction motor may be a wound rotor with slip rings or a squirrel cage rotor. The rotor of the switched reluctance motor is generally a salient pole type without a magnet. The rotor of a permanent magnet based machine is usually composed of rotor laminations surrounding the magnets.

In the case of stator construction, the stator is constructed by stacking laminations that are laser cut or stamped. These laminations are generally of the same shape and size throughout their length. This creates an extruded (extruded) appearance of the stator along the length direction. Winding is typically done around the stator teeth to produce the desired winding pattern.

An internal combustion engine for a vehicle is generally provided with a starter motor for starting the engine from zero speed. The starter motor draws energy from an energy storage medium, such as a battery. Additionally, the engine is also equipped with a magneto device for generating electrical power to charge the battery.

An Integrated Starter Generator (ISG) is a dedicated machine associated with an internal combustion engine. The ISG may be used to start the engine by spinning the engine until ignition is provided, and then be able to generate power from the induced voltage above an engine operating threshold speed.

Drawings

The detailed description is described with reference to the accompanying drawings. Throughout the drawings, the same reference numerals are used to refer to the same features and components.

Fig. 1 illustrates a left side view of an exemplary two-wheeled vehicle, in accordance with embodiments of the present subject matter.

Fig. 2 shows a typical cross section of an electrical machine according to an embodiment of the invention.

Fig. 3 illustrates a perspective view of a typical tooth of a motor according to an embodiment of the present invention.

FIG. 4 depicts a block diagram of a control system for assisting an internal combustion engine of a vehicle during startup and high speed operation, according to an embodiment of the present invention.

Fig. 5 illustrates a flow chart depicting a method for reducing losses and for increasing startability of an electric machine, in accordance with an embodiment of the present subject matter.

Detailed Description

The present invention describes an electric machine that exceeds the ISG in terms of function. The present invention is also designed to assist the engine at high speed, high load conditions so that vehicle and engine operation can be performed to reduce CO2 and NOx emissions.

Further, the present invention may be implemented with a variety of motor topologies, such as induction motors, Switched Reluctance Motors (SRMs), and BLDC (brushless direct current) motors. The induction motor and the switched reluctance motor operate with corresponding power electronic controllers that regulate torque based on input conditions, such as current rotational speed.

Although the speed of the induction motor and the SRM is not limited by the induced back emf (electromotive force), the speed range of the BLDC is affected due to the induced voltage. This is due to the rate of change of magnetic flux in the coil caused by the presence of the rotating magnet, thereby inducing a voltage in the winding coil. This voltage limits the current flowing into the motor, which limits the possible torque at speeds above zero, depending on the voltage supplied.

When the motor is designed for starting and power-assisted operation, the requirements are contradictory. Launch requires a high torque constant, while power assist requires high speed/power operation, and in turn requires a low torque constant.

In the present invention, a motor, such as a BLDC motor, is designed with a primary goal of startability of an engine. However, with such designs, the no-load speed of the motor is greatly limited by the back emf.

In view of the speed limitation of the BLDC, the BLDC motor is configured to have a smaller number of turns, so that the induced voltage is smaller, and thus the speed band is wider. This requires more current to be delivered to the motor coils during the start-up operation.

However, when high currents are passed through the stator coils, the resulting magnetic field may saturate the stator core material above a certain current threshold.

The invention proposes that an auxiliary winding with at least one tooth is wound around at least one of the stator teeth along any of the phases of the electrical machine. The ends of the wires are provided to a signal conditioning circuit that filters noise from the signal. The filtered signal is provided to an ADC (analog to digital converter) pin of the controller to digitize the signal value.

The voltage induced in the coil is proportional to the rate of change of flux linkage in the region of the coil. The proportionality constant depends on the number of turns of the auxiliary winding given by the following equation.

Phi＝∫v(t)*dt+C

The current flux in the stator teeth is determined by the increase in the value of the voltage captured in the controller over time. In one embodiment, the magnetic flux density of the stator teeth is determined based on the geometry of the stator teeth for a given electric machine as calculated below.

When the controller finds that the value of B exceeds a predetermined threshold, the controller limits the current flowing into the motor to a current value just before the threshold is reached.

The zero offset C from integration can be used to identify the position of the magnet relative to the teeth in a permanent magnet based motor. In an alternative embodiment, the stator comprises a temperature sensor for limiting the current based on a predetermined temperature.

ISG applications benefit from the present invention because it is possible to use thicker conductors with fewer strands. This allows the motor to operate at high speeds (due to the smaller induced voltage) and also produces more torque at start-up (due to the greater current that can be supplied to the motor). Its application to ISGs is not limiting and can be used for other applications. Any electric motor application may benefit from the present invention, which may be used in electric or hybrid vehicles, etc.

In one embodiment, the present subject matter provides an electric machine having one or more electrical phases. The motor is able to identify flux saturation and limit the current passing through to reduce losses and improve startability of the motor. The electric machine includes a stator having a stator core and a plurality of teeth disposed around a periphery of the stator core. Each of the plurality of teeth is wound with a wire having a predetermined thickness to form a winding. A rotor is provided that is rotatable by interaction with a magnetic field generated by a stator upon receiving electrical energy from at least one power source. The rotor is separated from the stator by an air gap. The plurality of teeth includes at least a first set of teeth corresponding to at least a first phase of the one or more electrical phases. The first set of teeth includes an auxiliary winding wound around at least one of the first set of teeth. In one embodiment, the rotor is arranged inside the stator. In an alternative embodiment, the rotor is arranged outside the stator.

In one embodiment, the magnetic field is perpendicular to the axis of rotation of the rotor. And in an alternative embodiment the magnetic field is parallel to the axis of rotation of the rotor.

In one embodiment, the auxiliary winding comprises at least one turn of wire wound around the at least one tooth. The rotor includes a plurality of permanent magnets arranged facing the plurality of teeth of the stator.

In one embodiment, the invention includes a control system for identifying flux saturation and limiting current flow therethrough to reduce losses and improve startability. The control system includes an electric machine having one or more electrical phases, the electric machine including a stator having a stator core and a plurality of teeth disposed about a periphery of the stator core. Each of the plurality of teeth is wound with a wire having a predetermined thickness to form a winding. The rotor is rotatable by interacting with a magnetic field generated by the stator when receiving electrical energy from at least one power source. The rotor is separated from the stator by an air gap, wherein the plurality of teeth includes at least a first set of teeth corresponding to at least a first phase of the one or more electrical phases. The first set of teeth includes an auxiliary winding wound around at least one of the first set of teeth.

In one embodiment, at least one energy storage device is provided. The energy storage device is configured to supply energy to the electric machine when the electric machine operates as a motor, and is configured to store energy generated by the electric machine when the electric machine operates as a generator.

Further, in one embodiment, the present subject matter describes a motor controller comprising at least one microcontroller. The motor controller includes a signal conditioning circuit capable of receiving a voltage output from at least one end of the auxiliary winding. At least one microcontroller is capable of receiving the conditioned signal from the signal conditioning circuit and detecting and comparing the magnetic flux of the stator core to a predetermined threshold of magnetic flux. In one embodiment, the signal is conditioned by scaling down the voltage and filtering out noise. The resulting conditioned signal is simply a scaled down voltage. The motor controller limits current through the motor when the magnetic flux of the stator core is greater than a predetermined threshold of magnetic flux.

In one embodiment, a microcontroller of a control system includes a pulse width modulation circuit that limits current through a motor by actuating one or more power electronic switches of the motor controller. In one embodiment, the signal conditioning circuit is a low pass filter and the threshold frequency for filtering is greater than the maximum electrical frequency of the motor.

Furthermore, in one embodiment, the electric machine enables limiting peak torque to approximately 50Nm to 52Nm at operating current both during vehicle launch and during powering of a powertrain (e.g., an internal combustion engine) while the vehicle is traveling.

In one embodiment, the present invention describes a method for identifying flux saturation and limiting current flow therethrough for reducing losses and providing startability. The method includes the step of operating the electric machine to start an internal combustion engine of the vehicle. The method further comprises the steps of: sensing, by a signal conditioning circuit of a motor controller, a voltage induced across an auxiliary coil wound around at least teeth of a first set of teeth of a stator of the motor. In one embodiment, the method includes determining, by a motor controller, a magnetic flux on the teeth of the stator based at least on a sensed voltage. The determined magnetic flux is then compared to a predetermined threshold value for the magnetic flux. In one embodiment, the method further comprises limiting, by the motor controller, current flow through the motor when the magnetic flux of the stator core is greater than a predetermined threshold of magnetic flux.

These and other advantages of the present subject matter will be described in more detail in the following description in conjunction with the accompanying drawings.

Fig. 1 illustrates a left side view of an exemplary two-wheeled vehicle, in accordance with embodiments of the present subject matter. The vehicle 100 has a frame assembly 105, the frame assembly 105 serving as a structural member and skeleton of the vehicle 100. The frame assembly 105 includes a head tube 105A, and the steering assembly is rotatably pivoted by the head tube 105A. The steering assembly includes a handlebar assembly 111 connected to a front wheel 115 by one or more front suspensions 120. The front fender 125 covers at least a portion of the front wheel 120. Further, the frame assembly 105 includes a main tube (not shown) extending rearward and downward from the head tube 105A. The fuel tank 130 is mounted to the main pipe 105A. Further, a down tube (not shown) extends substantially horizontally rearward from the rear of the main tube. Additionally, the frame assembly includes one or more rear tubes (not shown) extending obliquely rearward from the rear of the down tube. In the preferred embodiment, the frame assembly 105 is a single tube type that extends from the front F to the rear R of the vehicle 100.

In one embodiment, power unit 135 is mounted to the down tube. In one embodiment, power unit 135 comprises an IC engine. The fuel tank 130 is functionally connected to the power unit 135 to supply fuel. In a preferred embodiment, the IC engine is tilted forward, i.e. the piston axis of the engine is tilted forward. Further, the IC engine 135 is functionally coupled to the rear wheel 140. The swing arm 145 is swingably connected to the frame assembly 105, and the rear wheel 140 is rotatably supported by the swing arm 145. One or more rear suspensions 150 are connected at an angle to the swing arm 145, which bears both radial and axial forces due to wheel reactions. The rear fender 155 is disposed above the rear wheel 145. The seat assembly 160 is disposed at the rear R of the cross-over defined by the frame assembly 105. In one embodiment, seat assembly 160 includes a driver seat 160A, a rear seat 160B. Further, the rear seat 160B is positioned above the rear wheel 145. In addition, the vehicle 100 is supported by a center bracket (not shown) mounted to the frame assembly 105. The floor 165 is mounted to the down tube and disposed at the cross portion. The floor 165 covers at least a portion of the power unit 135. The vehicle 100 employs an auxiliary power unit (not shown), e.g., an energy storage device such as a battery, supported by the frame assembly 105. Additionally, the vehicle 100 is provided with at least one set of foot pedals 180 to enable the driver/rear seat passenger to rest their feet.

Fig. 2 shows a cross-section of an electrical machine according to an embodiment of the invention. In one embodiment, the motor is an external rotating BLDC motor. In one embodiment, an external rotating BLDC motor is used as an Integrated Starter Generator (ISG). The subject electric machine 101 includes a rotor 104, the rotor 104 further including a back iron 106 and a plurality of magnets 108 disposed on an inner surface of the rotor 104. In one embodiment, back iron 106 rotates along with the rotation of rotor 104. In one embodiment, the plurality of magnets 108 are permanent magnets.

Additionally, back iron 106 may be made of any of iron, silicon steel, which may be made as a single piece of iron or silicon steel. Alternatively, back iron 106 is fabricated as a layer of iron or silicon steel with a plurality of electrically insulating layers therebetween. In one embodiment, the plurality of magnets 108 may be any one of arc magnets and planar magnets. Further, in one embodiment, the plurality of magnets 108 are arranged circumferentially adjacent to each other without any gaps. Alternatively, the plurality of magnets 108 may be arranged circumferentially adjacent to each other with a circumferential air gap between two adjacent magnets of the plurality of magnets 108.

In addition, the electric machine 101 includes a stator 102, the stator 102 having a centrally disposed stator core 118, a plurality of stator teeth 112 circumferentially arranged about the stator core 118 forming a plurality of stator slots 114 therebetween. In one embodiment, the plurality of stator slots 114 are further filled with a plurality of windings 116. In one embodiment, the stator 102 is enclosed within the rotor 104 and radially separated by an air gap 110. In one embodiment, each of the plurality of stator teeth 112 includes a shank. In one embodiment, the stems of the teeth of the plurality of stator teeth 112 have equal widths at both ends of the stems (i.e., at a first end toward the stator core 118 and a second end away from the stator core). In an alternative embodiment, each slot of the plurality of stator slots 114 is formed to have an equal width at both ends (i.e., at an end closer to the stator core 118 and at an end further from the stator core 118) by two adjacent teeth of the plurality of stator teeth 112 having different widths at both ends thereof. In another alternative embodiment, each of the plurality of stator teeth 112 and each of the plurality of stator slots 114 are formed such that the widths of the teeth and slots at the ends are not equal. In one embodiment, the shank of each of the plurality of stator teeth 112 terminates with the head facing rotor 104, and the head has a width wider than the shank.

Fig. 3 shows a perspective view of a typical tooth 112 of the electric machine 101 according to an embodiment of the invention. In one embodiment, fig. 3 shows one of the stator teeth 112 having a primary winding 310 and an auxiliary winding 306. The auxiliary winding 306 is represented by a single strand 306 that surrounds the teeth 112. In one embodiment, stator teeth 112 have a head 302 and a shank 308. The head 302 faces the inner surface of the rotor 104. In one embodiment, the stem portion 308 has a smaller thickness than the head portion 302. In one embodiment, a side surface 304 of the head 302 separates two adjoining stator teeth 112. In one embodiment, each of the stator teeth 112 is wound with one or more primary windings 310. In one embodiment, motor 101 has an increased thickness of primary winding 310, which results in a smaller number of primary windings 310. This allows the motor 101 to operate at high speeds (due to the smaller induced voltage) and also produces more torque at start-up (due to the greater current that can be applied to the motor). In one embodiment, the application of the motor 101 of the present invention as an ISG is not limiting for other applications. Any motor may benefit from the present invention.

Further, in one embodiment, the present subject matter provides one or more electrical phases to the electric machine 101. The motor 101 is able to recognize the magnetic flux saturation and limit the current passing through to reduce losses and improve startability of the motor 101. The motor 101 includes a stator having a stator core and a plurality of teeth arranged around the periphery of the stator core. Each tooth 112 is wound with a wire having a predetermined thickness to form a primary winding 310. In one embodiment, the auxiliary winding 306 includes at least one turn of wire that is wound around the teeth 112 and along any one phase of the electric machine 101. The ends of the wires of the auxiliary winding 306 are provided to a signal conditioning circuit (as shown in fig. 4) that filters noise from the signal.

Fig. 4 depicts a block diagram of a control system 400 for assisting an internal combustion engine of the vehicle 100 during start-up and during high speed operation, according to an embodiment of the present invention. In one embodiment, the control system 400 includes a motor controller 402 that also includes at least one microcontroller 404 and signal conditioning circuitry 406. In one embodiment, the motor controller 402 is an ISG controller 402 that is powered by an energy storage device, e.g., a battery, that effectively operates the motor 101 both during start-up of the vehicle by providing boost to the motor 101 and during travel operation of the vehicle by providing voltage from the battery 410. In one embodiment, the microcontroller 204 is capable of processing signals received by the signal conditioning circuit 406 from the auxiliary winding 306. In one embodiment, signal conditioning circuit 406 can receive a voltage output from at least one terminal of auxiliary winding 306. The at least one microcontroller 404 can receive the conditioned signal from the signal conditioning circuit 406 and detect and compare the magnetic flux of the stator core to a predetermined threshold of magnetic flux. In one embodiment, the signal is conditioned by scaling down the voltage and filtering out noise. The resulting conditioned signal is simply a scaled down voltage. The motor controller 402 limits the current flowing through the motor 101 when the magnetic flux of the stator core is greater than a predetermined threshold of magnetic flux.

In one embodiment, the microcontroller 404 of the control system 400 includes a pulse width modulation circuit (not shown) that limits the current through the motor 101 by actuating one or more power electronic switches (not shown) of the motor controller 402. In one embodiment, the signal conditioning circuit 406 is a low pass filter and the threshold frequency for filtering is greater than the maximum electrical frequency of the electric machine 101 (e.g., Integrated Starter Generator (ISG) 101).

Fig. 5 shows a flowchart depicting a method 500 for reducing losses and for improving startability of electric machine 101, in accordance with an embodiment of the present subject matter. In one embodiment, at step 502, the method 500 involves operating the electric machine 101 to start the engine. In one embodiment, at step 504, the method 500 involves sensing a voltage induced across the auxiliary winding 306 of the electric machine 101 in order to determine a magnetic flux. Further, in one embodiment, at step 508, method 500 involves allowing the current flowing into motor 101 to increase before determining whether the induced magnetic flux is greater than a predetermined threshold of magnetic flux. In one embodiment, if it is determined that the magnetic flux is not greater than the predetermined threshold magnetic flux, the method 500 involves allowing the current to flow to the motor 101 to be further increased. However, in one embodiment, if it is identified that the determined magnetic flux is greater than the predetermined threshold, the method 500 involves limiting the current to the motor 101 by limiting the voltage at step 510. After limiting the current to the motor 101 in step 510, the method 500 further loops back to step 504 to again sense the voltage induced across the auxiliary winding 306.

Many modifications and variations of the present subject matter are possible in light of the above disclosure. Therefore, within the scope of the claims of the present subject matter, the disclosure may be practiced other than as specifically described.

Claims

1. An electric machine (101) having one or more electrical phases, the electric machine (101) being capable of identifying flux saturation and limiting current flow therethrough to reduce losses and improve startability of the electric machine (101), the electric machine (101) comprising:

a stator (102) having a stator core (118) and a plurality of stator teeth (112) arranged around a periphery of the stator core (118), each of the plurality of stator teeth (112) being wound with a wire having a predetermined thickness to form a winding; and

a rotor (104), the rotor (104) being rotatable by interaction with a magnetic field generated by the stator (102) upon receiving electrical energy from at least one power source, the rotor (104) being separated from the stator (102) by an air gap (110),

the plurality of stator teeth (112) comprising at least a first set of teeth corresponding to at least a first phase of the one or more electrical phases,

an auxiliary winding (306) configured to be wound around the stator teeth (112) of the first set of teeth to detect magnetic flux in the stator core (118);

wherein the auxiliary winding (306) is electrically configured to a motor controller (402); and is

Wherein the motor controller (402) is configured to receive a voltage output from the auxiliary winding (306).

2. The electrical machine (101) of claim 1, wherein the rotor (104) is arranged inside the stator (102).

3. The electric machine (101) according to claim 1, wherein the rotor (104) is arranged outside the stator (102).

4. The electric machine (101) of claim 1, wherein the magnetic field is perpendicular to an axis of rotation of the rotor (102).

5. The electric machine (101) of claim 1, wherein the magnetic field is parallel to an axis of rotation of the rotor (104).

6. The electric machine (101) of claim 1, wherein the auxiliary winding (306) comprises at least one turn of wire wound around the at least one tooth.

7. The electrical machine (101) of claim 1, wherein the rotor (104) has a plurality of permanent magnets (108) arranged facing the plurality of stator teeth (112) of the stator (102).

8. A control system (400) for identifying flux saturation and limiting current flow therethrough to reduce losses and improve startability, the control system (400) comprising:

an electric machine (101) having one or more electrical phases, the electric machine (101) comprising: a stator (102) having a stator core (118) and a plurality of stator teeth (112) arranged around a periphery of the stator core (118), each of the plurality of stator teeth (112) being wound with a wire having a predetermined thickness to form a winding; and a rotor (102), the rotor (104) being rotatable by interaction with a magnetic field generated by the stator (102) upon receiving electrical energy from at least one power source, the rotor (104) being separated from the stator (102) by an air gap (110); wherein the plurality of stator teeth (112) comprises at least a first set of teeth corresponding to at least a first phase of the one or more electrical phases, an auxiliary winding (306) configured to be wound around the stator teeth (112) of the first set of teeth to detect a magnetic flux in the stator core (118);

at least one energy storage device for supplying energy to the electric machine (101) when the electric machine (101) operates as a motor, and for storing energy generated by the electric machine (101) when the electric machine (101) operates as a generator; and

a motor controller (402) including at least one microcontroller (404), the motor controller (402) including a signal conditioning circuit (406), the signal conditioning circuit (406) capable of receiving a voltage output from at least one end of the auxiliary winding (306), the at least one microcontroller (404) capable of receiving a conditioned signal from the signal conditioning circuit (406) and detecting a magnetic flux of the stator core (118) and comparing the magnetic flux to a magnetic flux predetermined threshold, and the motor controller (402) limiting a current flowing through the motor (101) when the magnetic flux of the stator core (118) is greater than the magnetic flux predetermined threshold.

9. The control system (400) of claim 8, wherein the microcontroller (404) includes a pulse width modulation circuit that limits current through the motor (101) by actuating one or more power electronic switches of the motor controller (402).

10. The control system (400) of claim 8, wherein the signal conditioning circuit is a low pass filter and a threshold frequency for filtering is greater than a maximum electrical frequency of the motor (101).

11. A method for identifying flux saturation and limiting current therethrough for reducing losses and for improving startability of an electric machine, the method comprising:

operating the electric machine (101) to start the powertrain of the vehicle;

sensing, by a signal conditioning circuit (406) of a motor controller (402), a voltage induced across an auxiliary winding (306) wound around a stator tooth (112) in a first set of a plurality of stator teeth (112) of the motor (101);

calculating, by the motor controller (402), a magnetic flux across the stator teeth (112) in the first set of a plurality of stator teeth (112) based at least on the sensed voltage;

comparing the calculated magnetic flux with a predetermined threshold value of magnetic flux; and

limiting, by the motor controller (402), current flow through the motor (101) when a magnetic flux of a stator core (118) is greater than the magnetic flux by a predetermined threshold.